Lanolin Acid

Lanolin Acid is the mix of fatty acids you get when you split lanolin into its two halves: the alcohols and the acids.

This ingredient is a hard, waxy, yellow-tan solid and about 63% of its plain fatty acids and chain lengths run anywhere from 7-41 carbons (palmitic, stearic, and longer acids make up the bulk).

In formula, this ingredient acts as a cleansing surfactant or emulsifier.

Maximum concentrations range from 0.04% in leave-on products and 0.05% in rinse-off products; these levels have actually dropped down from 1-3% twenty years earlier.

Safety-wise, it's well studied and boring in a good way: it wasn't mutagenic and showed no developmental toxicity in rats up to 1000 mg/kg/day.

There are two caveats though:

1. Irritation: of all the lanolin ingredients, Lanolic Acid is the one flagged as a moderate skin irritant in animal testing. Undiluted, it was a mild to moderate eye irritant in 3/4 rabbit studies. That's why you'll usually see this ingredient in low-percetange or rinse-off roles.
2. Allergy: lanolin was the American Contact Dermatitis Society's 2023 Allergen of the Year, but the actual sensitizers are the free lanolin alcohols and not the acid fraction. Lanolin acid actually tested to be non-sensitizing in a mouse local lymph node assay at up to 50%.

This ingredient does have a comedogenic rating of 4, but this doesn't mean a formula with this ingredient will clog pores. Human testing has proved that any finished product with this ingredient won't automatically make you break out; it really comes down to concentration, formula, and your skin.

Due to the palmitic and stearic acids, this ingredient may not be fungal acne safe.